This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To determine the distribution pattern of estrogen receptor-alpha in the brainstem and spinal cord of ovariectomized female monkeys to understand the role of estrogen in women's health. Because estrogen dependency in sexual behaviors differs in primates and rodents, the distribution pattern of estrogen receptors in the brainstem and spinal cord of primates would be quite different. However, to date there is little information on this topic in primates. The results suggest that in contrast to the presence of estrogen receptor-alpha containing neurons in a widespread area in the rodent brainstem and spinal cord, they are concentrated to regions involved in vicero-sensory, auditory, and autonomic processing in rhesus monkey. Estrogen treatment did not result in significant differences in the distribution pattern of estrogen receptor immunoreactive neurons. Therefore, estrogen action through estrogen receptor-alpha plays a modest role in function of the brainstem and spinal systems in primates. Moreover, there is qualitative and quantitative differences in the distribution of ER-_ IR neurons in the primates and mice brainstem and spinal cord, suggesting that in primates ER-_ plays a more modest role in control of estrogen-mediated behaviors as compared to rodents. This research used WNPRC Animal Services. This work was supported by supplemental funding to RR00167 (1997-1998) and a publication has resulted during this reporting period.